Flame arrestor for internal combustion engines



March 1, 1966 H. D. DAlGH 3,237,617

' FLAME ARRESTOR FOR INTERNAL COMBUSTION ENGINES Filed March 24, 1965United States Patent 3,237,617 FLAME ARRESTOR FOR INTERNAL COMBUSTIONENGINES Harold D. Daigh, Rolling Hills Estates, Calif., assignor toRichfield Oil Corporation, Los Angeles, Calif., a corporation ofDelaware Filed Mar. 24, 1965, Ser. No. 442,321 3 Claims. (Cl. 123-119)This invention relates to recovery of crankcase fumes from an internalcombustion engine and more particular- 1y relates to a flame arrestorfor arresting flame propagation through a crankcase ventilation system.

Many proposals have been made to return crankcase blowby fumes throughconduits to the induction system of an internal combustion engine, andsuch systems generally provide a check valve or other valve mechanism inthe conduit between the crankcase and the intake manifold. This valvevaries an opening in such conduit in response to predeterminedconditions to control the passage of fumes from the crankcase to theintake manifold through the conduit.

Engine backfires result in flame propagation through the inductionsystem and any conduits in open communication therewith, thus exposingthe aforementioned recycle conduits to such flames. Flame propagationthrough the crankcase recycle conduit into the crankcase could result ina dangerous explosion in the crankcase as could propagation of the flamethrough the carburetor and the air cleaner through a fresh air lineconnecting the air cleaner with the rocker arm cover. Hence, it isdesirable to provide a flame arrestor in any conduits connected with theinduction system in order to prevent flame propagation into areas whichwould result in explosions.

Flame arrestors of the prior art such as check valves, mesh screen, etc.must be replaced or cleaned periodical ly since the buildup of dirt,grime, etc. on the flame arrestor will restrict the flow of gasesthrough the conduit. Furthermore, these flame arrestors are lesseffective in preventing flame propagation when the flame arrestorsurface is covered with dirt and grime. Relatively stifi coil springshave heretofore been proposed as flame arrestors, however, such springswere not self-cleaning nor able to expand or compress sufliciently togive any appreciable benefit.

It is, therefore, an object of my present invention to provide aself-cleaning flame arrestor for positioning in conduits communicatingwith the induction system of an internal combustion engine.

Other objects and a more complete understanding of my present inventionmay be had by reference to the following specification and the appendedclaims when taken in conjunction with the drawings, wherein:

FIG. 1 shows in partial cross section an internal combustion engineequipped with a crankcase ventilation system;

FIG. 2 shows an enlarged cross-sectional view taken on line 2-2 of FIG.1 showing the flame arrestor of my present invention positioned in acrankcase recycle conduit;

FIG. 3 shows an enlarged cross-sectional view of the flame arrestor ofmy present invention in a modified tube or pipe adapted to receive theflame arrestor.

Briefly described, my present invention relates to a self-cleaning flamearrestor positionable in a conduit and designed to be sufficientlyflexible to move in response to the passage of fluids through saidconduit.

Referring now more particularly to the drawings, FIG. 1 shows aninternal combustion engine wherein fumes from the crankcase arecollected through the oil fill pipe 12 and passed through a conduit 14which com- 3,237,617 Patented Mar. 1, 1966 municates with the intakemanifold 16 below the carburetor 18. With this ventilation system, therecycled crankcase fumes are mixed with the incoming charge from thecarburetor and passed into the combustion chamber 20 when the intakevalve 22 is opened.

In the above-mentioned crankcase ventilating system, the engine shouldbe essentially sealed to the escape of fumes. A continual supply offresh air may be supplied from the clean side of the air cleaner 24through conduit 26. The passage of crankcase fumes through the conduit14 is controlled by a recycle valve 28, as disclosed in my Patent No.3,077,871, issued February 19, 1963 for crankcase Ventilating System forInternal Combustion Engines, or any of the many crankcase recyclecontrol valves available to those skilled in the art.

A backfire in the combustion chamber 20 gives rise to a flame which ispropagated through the induction system and carburetor and,consequently, out through any openings therein. The propagation of aflame through the conduit 14 to the crankcase could result in a seriousengine fire as could the entry of a flame into the rocker arm coverthrough the fresh air line 26 from the clean air side of the air cleaner24. Consequently, it is desirable to insert flame arrestors in anyconduits leading from the induction system, such as conduit 14 leadingfrom the intake manifold, or conduit 26 leading from the air cleaner, ata point close to the induction system.

Conventionally, a wire mesh screen, for example, as shown at 33 in FIGS.2 and 3 of the aforementioned patent, is positioned in the conduit toquench the flame propagation. As shown in FIG. 2, my present inventionprovides a novel tapered cone flame arrestor 30 positioned in theconduit 14 with the tapered coil end 32 facing the flame, that is,facing downstream or towards the intake manifold. Where the conduit 14is of a sufficiently flexible material, such as rubber, the flamearrestor 30 may be helically twisted into place, and the flame arrestorat its larger end should be of a size slightly larger than the insidediameter of the flexible conduit 14 so that the flame arrestor willresist the tendency to migrate further into the conduit towards thecrankcase. The flame arrestor 30 may be installed also in line 26 withthe tapered coil end 32 of the spring facing the air cleaner 24. Where ametal conduit is utilized, as shown in FIG. 3, internal threads 38 maybe provided in the conduit 40 into which the large end of the taperedcoil 42 may be threaded.

With the flame arrestor 30 positioned with the tapered coil end facingthe induction manifold, the normal flow of gases through the conduit 14would tend to elongate the flame arrestor coil or open the same, thusfacilitating the flow of gases past the flame arrestor; however a flamepropagated from the opposite direction, that is, from the inductionmanifold through the conduit, would tend to cause the flame arrestorspring 30 to compress, thus advantageously providing a greater mass offlame quenching material to absorb or quench the heat from the flame.Although the precise mannner in which a flame is arrested by spring 30is not fully understood, it is also theorized that the spring whencompressed may arrest the flame without heat absorption or quenching, asby sharply reducing the oxygen supply. The effectiveness of thecompression of the spring in quenching the flames appears to beconfirmed by the fact that when the flame arrestor 30 is turned aroundso that the tapered coil end 32 faces the crankcase, a flame may bepropagated past the flame arrestor device 30.

Although my present invention has been described herein with respect toa particular embodiment with a certain degree of particularity, thescope of my present invention should not be so limited but should beafforded the full scope of the appended claims.

I claim:

1. In a crankcase ventilating system for internal combustion engineshaving an opening in the engine above the oil level through which blowbyfluids can escape the engine and conduit means providing fluidcommunication between said opening and the induction system of saidengine from which a backfire flame may be propagated, said opening beingsubject to the crankcase pressure, the improvement comprising:

a flexible tapered coil flame arrestor positioned in said conduit withthe smaller end of said coil facing said induction system.

2. In a crankcase ventilating system for internal combustion engineshaving an opening in the engine above the oil level through which blowbyfluids can escape the engine and conduit means providing fluidcommunication between said opening and the induction system of saidengine, said opening being subject to the crankcase pressure, theimprovement comprising:

a heat conductive flexible helical member positioned in said conduitwith the apex of said helical member oriented towards said inductionsystem, the tapered portion of said helical member being free to move orvibrate with the passage of fluids through said conduit from saidcrankcase to said induction system, said helical member tending toelongate when said fluids are passed through said conduit from saidcrankcase to said induction system, said member tending to compress whenthe flame is propagated through said conduit and contacts the apex ofsaid helical member.

3. The apparatus of claim 1 including an air cleaner device attached tosaid induction system and a conduit extending between said air cleanerand said crankcase, said latter conduit being opened to permit thepassage of fresh air from said air cleaner to said crankcase, and asecond tapered coil flame arrestor positioned in said second conduitwith the tapered coil end of said conduit oriented towards said aircleaner.

References Cited by the Examiner UNITED STATES PATENTS KARL J. ALBRECHT,Primary Examiner.

1. IN A CRANKCASE VENTILATING SYSTEM FOR INTERNAL COMBUSTION ENGINES HAVING AN OPENING IN THE ENGINE ABOVE THE OIL LEVEL THROUGH WHICH BLOWBY FLUIDS CAN ESCAPE THE ENGING AND CONDUIT MEANS PROVIDING FLUID COMMUNICATION BETWEEN SAID OPENING AND THE INDUCTION SYSTEM OF SAID ENGINE FROM WHICH A BACKFIRE FLAME MAY BE PROPAGATED, SAID OPENING BEING SUBJECT TO THE CRANKCASE PRESSURE, THE IMPROVEMENT COMPRISING: A FLEXIBLE TAPERED COIL FLAME ARRESTOR POSITIONED IN SAID CONDUIT WITH THE SMALLER END OF SAID COIL FACING SAID INDUCTION SYSTEM. 